Motor fuel compositions



United States Patent 3,212,867 MOTOR FUEL COMPOSITIONS Nelson E. Ockerhloom, Haddonfield, N.J., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing. Filed Mar. 2, 1961, Ser. No. 92,767 2 Claims. (Cl. 44-71) This invention relates to gasoline motor fuels for sparkignition, internal combustion engines. More particularly, the invention is directed to novel motor fuel compositions containing a small amount of a two-component additive combination consisting of a fundamentally-aromatic, primary or secondary amine, together with a monocarboxylic acid or one of certain derivatives thereof. It has been found that this novel additive combination provides a synergistic improvement in the octane quality of a substantially parafiinic hydrocarbon base fuel, either in the presence or in the absence of an organo-lead compound such as tetra-ethyl lead.

It is known in the art that certain classes of organic compounds, such as the primary and secondary aromatic amines, are effective for improving the octane quality of motor fuels such as gasoline. It is also known that certain organo-metallic compounds are similarly effective. For example, organo-lead compounds, and particularly tetra-alkyl lead compounds, have achieved widespread commercial useage in this application. Examples of tetraalkyl lead compounds which have been found to be effective as octane improvers are tetra-methyl lead, tetra-ethyl lead, monomethyl triethyl lead, dimethyl diethyl lead, trimethyl monoethyl lead, tetra-isopropyl lead, tetra-amyl lead and the like. Mixtures of such compounds have also been employed.

More recently, it has been disclosed that monocarbox- .ylic acids and certain of their derivatives which will yield a carboxyl radical under combustion chamber conditions are effective as adjuvants for the knock-suppressing effectiveness of tetra-alkyl lead anti-knock compounds under certain, limited conditions. Thus, in order to achieve any octane improvement whatsoever from these carboxyl-containing additives, it is first of all necessary that they be employed in combination with a tetra-alkyl lead antiknock compound such as tetra-ethyl lead. Furthermore, and even more significantly, it is essential to the achievement of the foregoing effect, that the hydrocarbon base fuel in which the combination of a carboxylic compound and a tetra-alkyl lead compound is employed be of the relatively non-parafiinic type, i.e., that such hydrocarbon fuel comprise at least percent by volume of aromatic and/or olefin hydrocarbons. Thus, it has been demonstrated that in substantially parafiinic fuels, such as those to which the instant invention pertains, the carboxylic compound is not effective for enhancing the anti-knock eifectiveness of the tetra-alkyl lead compound, and furthermore is not an octane improver by itself.

It has further been disclosed that, in hydrocarbon motor fuels comprising at least 10 percent by volume of aromatic and/or olefin hydrocarbons, and in the presence of a tetra-alkyl lead anti-knock compound, primary and secondary aromatic amines will co-act in combination with the carboxylic compound to further enhance the effectiveness of the tetra-alkyl lead anti-knock compound. However, as has heretofore been disclosed, it is essential to such a benefit that the hydrocarbon base fuel contain a minimum of at least 10 percent by volume of aromatic 3,212,867 Patented Oct. 19, 1965 ice and/or olefin hydrocarbons, and also that such fuel contain an anti-detonant amount of a tetra-alkyl lead antiknock compound.

In view of the foregoing, it would be desirable to provide a novel additive material which would be effective for promoting a substantial octane improvement in hydrocarbon base fuels of the paratfinic type, i.e., in hydrocarbon base fuels comprising significantly less than about 10 percent by volume of aromatic and/or olefin hydrocarbons. The provision of such an additive material is a specific object of this invention.

It has now been discovered that, in substantially paraffinic hydrocarbon motor fuels, the novel combination of a fundamentally-aromatic, primary or secondary amine together with a monocarboxylic acid or one of certain derivatives thereof will provide a synergistic octane improve ment, either in the presence or in the absence of an organo-lead anti-knock compound. This discovery is all the more surprising in the light of prior art teachings, which teachings require both the presence of a tetra-alkyl lead compound and a relatively nonparaffinic character for the hydrocarbon base fuel in order to achieve any octane improvement whatever from the combination of an aromatic amine with a carboxylic compound.

In practicing the invention, one or more fundamentally-aromatic, primary or secondary amines of certain types can be employed as one component of the novel two-coin ponent additive combination. Suitable types of amines are the primary and secondary arylamines, primary and secondary alkarylamines, mixed aryl-alkaryl secondary amines, mixed aryl-aralkyl secondary amines, mixed alkaryl-aralkyl secondary amines and certain alkyl-substituted derivatives of the two last-mentioned types. The particular amines which can be suitably employed in practicing this invention are thus represented by the following generic formulae:

and

wherein x represents the number of successive divalent methylene groups and is selected from the group corisisting of 0, 1 and 2. The permissible benzene-ring substituents denoted by the symbols, R through R are each selected from the group consisting of hydrogen and alkyl radicals having less than about 6 carbon atoms each. Specific, but non-limiting, examples of suitable amines include: phenylamine (aniline); 4-methyl-phenylamine (ptoluidine); 2-propyl-phenylamine; 2,3-dimethyl-phenylamine (2,3-xylidine); 3-ethyl-5-butyl-phenylamine; diphenylamine; 2 -methyl-diphenylamine (N-p'henyl-o-toluidine); 2,6-diethyl-3-propyl-4'-pentyl dip'henylamine; N-phenyl-benzylamine; N-phenyl-fl-phenylethylamine; N- phenyl-Z-propyl-benzylamine; N-4-butyl-phenyl benzylamine; N-5,6-dimethyl phenyl-Z-ethyl-4-pentyl-/3-phenylethylamine and the like. Mixtures of the above, and of similarly suitable amines, can also be used. In addition, either a pure isomer or a mixture of different isomers of one or more suitable amines can be employed. For example, a commercial mixture of the toluidine isomers, such as 60 volume percent ortho-, 36 volume percent para and 4 volume percent meta-, can conveniently be used.

Normally, additive amounts of the amine or mixture of amines in the range of from about 0.1 volume percent to about 5 volume percent of the resulting gasoline composition are suitable and give good results. However, concentrations in the range of from about 0.5 to about 2.5 volume percent give excellent results and are preferred. On occasion, amounts outside of the above-recited ranges can also be used.

As stated heretofore, it is also essential to the successful practice of this invention that a monocarboxylic acid, or suitable derivative thereof, be employed as the second, or carboxylic, component of the novel additive combination herein disclosed. Suitable carboxylic compounds are those represented by any of the following generic formulae, and include the monocarboxylic acids, the ethermonocarboxylic acids and keto-monocarboxylic acids, anhydrides and tertiary alkyl esters of any of the foregoing, the aldehydes, and certain diesters of monocarboxylic wherein: R is hydrogen or a monovalent hydrocarbon radical of 1 to 29 carbon atoms; R, is a divalent hydrocarbon radical of 1! to 18 carbon atoms; R,- is hydrogen or a tertiary alkyl group of 4 to 18 carbon atoms; each of R R R and R is either hydrogen or a monovalent hydrocarbon or heterocyclic radical of not more than 6 carbon atoms; X is oxygen or a carbonyl group, n and m are each either 0 or 1, and the total number of carbon atoms in R R and X is not more than 29.

Non-limiting examples of suitable monocarboxylic acids and anhydrides are formic, acetic, propionic, caproic, 2- ethylhexoic, capric, lauric, steric, benzoic, and phenylacetic acids and their anhydrides. Non-limiting examples of suitable etherand keto-monocarboxylic acids and anhydrides include methoxyacetic, ethoxyacetic, phenoxyacetic, 3-ethoxypropionic, o-ethoxybenzoic, 4-keto-ster-ic, 3-keto-n-hexanoic and 3-phenyl-3-keto-propionic acids and their anhydrides. Tertiary alkyl esters of suitable acids are especially preferred, and non-limiting examples of such useful esters include tertiary-butyl acetate, tertiary-butyl formate, tertiary-amyl propionate, tertiaryamyl capronate and tertiary-butyl laurate. Non-limiting examples of suitable aldehydes include benzaldehyde, nbutyraldehyde, isobutyraldehyde, propionaldehyde, paraldehyde, lauraldehyde and tolual-dehyde. Non-limiting examples of suitable alkylidene, alkenylidene and other diesters of monocarboxylic acids include methylene diacetate, ethylidene diacetate, 2-propenylidene diacetate, propylidene diacetate, furfurylidene diacetate and possible position isomers of the foregoing.

Normally, additive amounts of the carboxylic compound, or mixture of such compounds, in the range of from about 0.1 volume percent to about 5.0 volume percent of the resulting gasoline composition are suitable and give good results. However, concentrations in the range of from about 0.2 to about 1.5 volume percent give better results and are preferred. On occasion, amounts outside of the above-cited ranges can also be used.

Conventional gasolines intended for use as fuels in spark-ignition internal combustion engines are distillate fractions of petroleum hydrocarbons which boil within the so-called gasoline range. For automotive engines, this range extends from about 80 F. to about 440 F., and

more usually from about F. to about 400 F., at atmospheric pressure. Aviation gasolines have a more narrow atmospheric boiling range, generally extending from a minimum of about 100 F. to a maximum of about 350 F. The novel additive combination of this invention can be employed with gasolines of either the automotive or aviation type, subject only to the express limitations regarding hydrocarbon-type composition which are set forth hereinafter.

The fraction of petroleum hydrocarbon designated as gasoline normally comprises hydrocarbons of all different types such as, for example, straightand branched-chain parafiins, cycloparafiins, olefins and aromatics. Generally, the proportions in which these hydrocarbon types are present in conventional gasolines vary over rather wide ranges. However, this invention is applicable only to base gasolines which comprise substantially less than 10 volume percent of olefins and/or aromatics. Specifically, the base fuel must comprise at least percent by volume of saturated hydrocarbons, viz., straightor branched-chain paratfins and cycloparaflins. Subject to this limitation, the remainder of the hydrocarbons in the gasoline can comprise any of the foregoing types in any and all proportions. While significant benefits are obtained from the practice of this invention with base gasolines containing the above-stated minimum concentration of saturated, or parafiin, hydrocarbons, it has been found that, within limits, even better results are achieved when the paraflinicity of the base fuel is even higher, i.e., when the base hydrocarbon fuel comprises even more than 95 percent by volume of saturated, or paraffin, hydrocarbons. For example, application of this invention to gasolines comprising not less than about 97 volume percent (or even more) of paraflin hydrocarbons give superior results and is preferred.

It is to be further understood that the primary gaso lines which are blended in accordance with the method of this invention can contain any of the additives eorn= monly employed in the art such as, for example, other anti-knock agents, scavengers, anti-icing agent's, detergents, corrosion inhibitors, stabilizers, spark plug fouling and surface ignition inhibitors, dyes and the like. With re spect to such additives, present-day gasolines normally contain at least a scavenger for the organo-lead anti knock compound, such as volatile halohydrocarbons for TEL. The presence of any and all such additives in effective concentrations in no way interferes with the practice of this invention and is expressly contemplated.

In order to illustrate the practice and unexpected benefits of this invention with a particular amine, namely, diphenyl amine, and with a particular carboxylic compound, namely, tertiary-butyl acetate, a substantially parafiinic gasoline was employed as the base fuel for a number of comparative tests. This base fuel was an aviation alkylate having the following volumetric hydrocarbontype composition: 97 percent saturated hydrocarbons (in cluding normaland iso-parafiins and cycloparaflins); 2 percent aromatics; and 1 percent olefins. This base fuel was divided into two major portions. To the first portion was added 3 cos. of tetra-ethyl lead per gallon, together with the customary accompanying amounts of halo-hydrocarbon lead scavengers. The other portion of the base gasoline was employed without the addition of an organolead anti-knock compound.

In order to demonstrate the synergistic octane improvement obtained from the use of a combination of diphenyl amine and tertiary-butyl acetate in the non-leaded portion of the foregoing parafiinic base fuel, diphenyl amine, tertiary-butyl acetate, and a mixture thereof were incorporated in individual samples of the non-leaded base fuel in the amounts hereinafter specified. The octane quality of the resulting samples was then determined by means of the Research Method (ASTM D-908), with the results shown in the following Table I.

Key: TBA=tertiary-butyl acetate; DPA=diphenyl amine.

In order to demonstrate the synergistic octane improvement obtained from the use of a combination of diphenyl amine and tertiary-butyl acetate in the leaded portion of the foregoing paraffinic base fuel, the hereinafter specified amounts of diphenyl amine, tertiary-butyl acetate, and both diphenyl amine and tertiary-butyl acetate were incorporated in individual samples of the leaded base fuel. The research octane number of the resulting samples was then determined by the Research Method (ASTM D1656) for motor fuels above 100 octane number, with the results shown in the following Table II.

Table II Research Octane Number (R.O.N.)

With 3.0 cc. Gain from Synergistic TEL per Additives Gain from Gallon Combination Base fuel 107. 1 Base fuel+0.75 vol. percent TBA. 107. 1 0.0 Base luel+1.0 vol. percent DPA 109. 4 2. 3 Base fuel+0.75 vol. percent TBA +1.0 vol. percent DPA 110. 4 3. 3 +1. 0

Key: TBA=tertiary-butyl acetate; DPA=diphenyl amine.

It is evident from the foregoing data that, in a substantially paraffinic base gasoline, and either in the presence or in the absence of an organo-lead anti-knock compound, the novel combination of a suitable aromatic amine with a suitable carboxylic compound provides a syngeristic improvement in the octane quality of that base gasoline. When other motor fuel compositions within the scope of the foregoing disclosure are similarly prepared and tested, substantially similar results are obtained.

The invention claimed is:

1. Gasoline fuel composition consisting essentially of (1) a major amount of saturated petroleum hydrocarbons boiling within the gasoline range comprising a least by volume paraffinic hydrocarbons; (2) a minor amount of diphenyl amine; and (3) a minor amount of a tertiary butyl acetate.

2. Gasoline fuel composition according to claim 1 wherein the amounts of diphenyl amine and tertiarybutyl acetate each are in the range of 0.2-1.5% by volume.

References Cited by the Examiner UNITED STATES PATENTS 1,605,664 11/26 Kettering et a1. 4474 2,210,942 8/40 Lipkin 4477 2,228,662 1/41 Holm 4470 2,461,917 2/49 Orelup 4474 2,504,361 4/50 Van Hartesveldt 252386 3,009,792 11/ 61 Eckert et a1. 4466 3,009,793 11/61 Eckert et a1. 4466 FOREIGN PATENTS 837,965 11/ 38 France. 571,921 10/58 Belgium.

OTHER REFERENCES Texaco Abstract of Australian Patent 42,139, Oct. 8, 1958.

Improved Motor Fuels Through Selective Blending, by Wagner et al., paper presented before 22nd Annual Meeting of the American Petroleum Institute, Nov. 7, 1941 (19 pp.).

DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner. 

1. GASOLINE FUEL COMPOSITION CONSISTING ESSENTIALLY OF (1) A MAJOR AMOUNT OF SATURATED PETROLEUM HYDROCARBONS BOILING WITHIN THE GASOLINE RANGE COMPRISING A LEAST 95% BY VOLUME PARAFFINIC HYDROCARBONS; (2) A MINOR AMOUNT OF DIPHENYL AMINE; AND (3) A MINOR AMOUNT OF A TERTIARY BUTYL ACETATE. 